title: Association between MGMT promoter methylation and non-small cell lung cancer: a meta-analysis.
abstract: BACKGROUND
  O(6)-methylguanine-DNA methyltransferase (MGMT) is one of most important DNA repair enzyme against common carcinogens such as alkylate and tobacco. Aberrant promoter methylation of the gene is frequently observed in non-small cell lung cancer (NSCLC). However, the importance of epigenetic inactivation of the gene in NSCLC published in the literature showed inconsistence. We quantified the association between MGMT promoter methylation and NSCLC using a meta-analysis method.
  
  
  METHODS
  We systematically reviewed studies of MGMT promoter methylation and NSCLC in PubMed, EMBASE, Ovid, ISI Web of Science, Elsevier and CNKI databases and quantified the association between MGMT promoter methylation and NSCLC using meta-analysis method. Odds ratio (OR) and corresponding 95% confidence interval (CI) were calculated to evaluate the strength of association. Potential sources of heterogeneity were assessed by subgroup analysis and meta-regression.
  
  
  RESULTS
  A total of 18 studies from 2001 to 2011, with 1, 160 tumor tissues and 970 controls, were involved in the meta-analysis. The frequencies of MGMT promote methylation ranged from 1.5% to 70.0% (median, 26.1%) in NSCLC tissue and 0.0% to 55.0% (median, 2.4%) in non-cancerous control, respectively. The summary of OR was 4.43 (95% CI: 2.85, 6.89) in the random-effects model. With stratification by potential source of heterogeneity, the OR was 20.45 (95% CI: 5.83, 71.73) in heterogeneous control subgroup, while it was 4.16 (95% CI: 3.02, 5.72) in the autologous control subgroup. The OR was 5.31 (95% CI: 3.00, 9.41) in MSP subgroup and 3.06 (95% CI: 1.75, 5.33) in Q-MSP subgroup.
  
  
  CONCLUSIONS
  This meta-analysis identified a strong association between methylation of MGMT gene and NSCLC. Prospective studies should be required to confirm the results in the future.
authors.affiliation: Department of Epidemiology and Biostatistics and the Ministry of Education Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Changmei
authors.initials: C
authors.lastname: Gu
authors.forename: Jiachun
authors.initials: J
authors.lastname: Lu
authors.forename: Tianpen
authors.initials: T
authors.lastname: Cui
authors.forename: Cheng
authors.initials: C
authors.lastname: Lu
authors.forename: Hao
authors.initials: H
authors.lastname: Shi
authors.forename: Wenmao
authors.initials: W
authors.lastname: Xu
authors.forename: Xueli
authors.initials: X
authors.lastname: Yuan
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Yang
authors.forename: Yangxin
authors.initials: Y
authors.lastname: Huang
authors.forename: Meixia
authors.initials: M
authors.lastname: Lu
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics*; D016022:Case-Control Studies; D019175:DNA Methylation; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics*; D011401:Promoter Regions, Genetic